| Sumario: | Objectives: We can expect that during the amplification of traveling wave produced by click stimulus each outer hair cell (OHC) produces some additional acoustic activity, and this activity reaches the ear canal. The reasonable assumption is that this activity is similar in shape for all OHC, but differs both in time scale and latency. It can be shown that for homogeneous cochlea almost all components of this activity are mutually suppressed, but each irregularity or lack of OHC will produce uncompensated response. Therefore, we can expect that transient evoked otoacoustic emission (TEOAE) should have components similar in shape but with duration almost proportional to latency. Material and methods: For verification of this hypothesis TEOAE data obtained in response to click stimulation were collected from 5 normally hearing volunteers using ILO probe, professional sound card and preamplifier of custom design. The data were averaged off-line using weighted averaging in time and frequency cells. Then the dominant components not corresponded to this hypothesis were removed and the blind deconvolution was applied to the rest of signal. For calculation of the exact relationship between time scale and latency of components the appropriate optimization was applied. All algorithms were carefully optimized and tested on a large set of modeled data and on a data obtained without stimulation. It was approved that the algorithm didn't produce false components, but the modeled components of different shapes were detected without disturbance. Results: For all records the algorithm produces a pattern like a tone burst with almost constant amplitude, sharp cut-off and a splash on first periods. Conclusions: It was shown that at least a part of TEOAE signal can be explained by proposed hypothesis. We digitally simulated a wide hole in rows of OHC. It was found that the maximal amplitude of uncompensated response is only 50 times greater for wide hole than for a lack of single OHC and the amplitude decreases for wider damages. Therefore, serious impairments shouldn't produce significant responses on its bounds. The shape of activity can also give some explanation for the effect of spectral periodicity of TEOAE demonstrated by George Zweig and Christopher Shera.
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